Dear friend,
you write: “When reality is best expressed by silence, and could be said to be silence itself, are not all forms of teaching a kind of dumbing down? To teach requires a certain nod to duality: there is the teacher and the taught; me and you.”
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Truth is expressed by silence and this silence is the perfume of the awakened mind and not the superficial silence of words and language.
The language of the rishis is imbued with silence and does not presume a teacher and a teaching. This silence is not available to the minds that reside in words. It is available to those who listen with/from the heart.